The Last Interesting Rover Had A Gas Turbine Engine

If you have a car parked outside as you are reading this, the overwhelming probability is that it has a reciprocating piston engine powered by either petrol(gasoline), or diesel fuel. A few of the more forward-looking among you may own a hybrid or even an electric car, and fewer still may have a piston engine car powered by LPG or methane, but that is likely to be the sum of the Hackaday reader motoring experience.

We have become used to understanding that perhaps the era of the petroleum-fueled piston engine will draw to a close and that in future decades we’ll be driving electric, or maybe hydrogen. But visions of the future do not always materialize as we expect them. For proof of that, we only need to cast our minds back to the 1950s. Motorists in the decade following the Second World War would have confidently predicted a future of driving cars powered by jet engines. For a while, as manufacturers produced a series of prototypes, it looked like a safe bet.

The Chrysler gas turbine car from [Brian]'s article. CZmarlin [Public domain].
The Chrysler gas turbine car from [Bryan]’s article. CZmarlin [Public domain].
Back in August, my colleague [Bryan] wrote a feature: “The Last Interesting Chrysler Had A Gas Turbine Engine“, in which he detailed the story of one of the more famous gas turbine cars. But the beautifully styled Chrysler was not the only gas turbine car making waves at the time, because meanwhile on the other side of the Atlantic a series of prototypes were taking the gas turbine in a slightly different direction.

Rover was a British carmaker that was known for making sensible and respectable saloon cars. They passed through a series of incarnations into the nationalized British Leyland empire, eventually passing into the hands of British Aerospace, then BMW, and finally a consortium of businessmen under whose ownership they met an ignominious end. If you have ever wondered why the BMW 1-series has such ungainly styling cues, you are looking at the vestiges of a Rover that never made it to the forecourt. The very successful Land Rover marque was originally a Rover product, but beyond that sector, they are not remembered as particularly exciting or technically advanced.

The Rover Jet1 prototype. Allen Watkin [CC BY-SA 2.0].
The Rover JET1 prototype. Allen Watkin [CC BY-SA 2.0].
At the close of the Second World War though, Rover found themselves in an interesting position. One of their contributions to war production had been the gas turbine engines found in the first generation of British jet aircraft, and as part of their transition to peacetime production they began to investigate civilian applications for the technology. Thus the first ever gas turbine car was a Rover, the 1950 JET1. Bearing the staid and respectable styling of a 1950s bank manager’s transport rather than the space-age look you might expect of the first ever gas turbine car, it nonetheless became the first holder of the world speed record for a gas turbine powered car when in 1952 it achieved a speed of 152.691 MPH.

The JET1 was soon followed by a series of further jet-powered prototypes culminating in 1956’s T3 and 1961’s T4. Both of these were practical everyday cars, the T3, a sports coupé, and the T4, an executive saloon car whose styling would appear in the 1963 petrol-engined P6 model. There was also an experimental BMC truck fitted with the engine. The P6 executive car was produced until 1977, and all models were designed to have space for a future gas turbine option by having a very unusual front suspension layout with a pivot allowing the spring and damper to be placed longitudinally in the front wing.

The Rover-BRM racing car at Gaydon. David Merrett [CC BY 2.0].
The Rover-BRM racing car at Gaydon. David Merrett [CC BY 2.0].
It was not only prototypes for production cars with gas turbines that came from Rover in the 1960s though, for in 1963 they put their gas turbine into a BRM racing chassis and entered it into the Le Mans 24 hour endurance race. It returned in the 1964 season fitted with a novel rotating ceramic honeycomb heat exchanger to improve its efficiency, racing for a final season in 1965.

The fate of the gas-turbine Rovers would follow that of their equivalent cars from other manufacturers including the Chrysler covered by [Bryan]. Technical difficulties were never fully overcome, the increasing cost of fuel  made gas turbine cars uneconomic to run, and meanwhile by the 1960s the piston engine had improved immeasurably over what had been available when the JET1 had been produced. The Rover P6 never received its gas turbine, and the entire programme was abandoned. Today all the surviving cars are in museums, the JET1 prototype in the Science Museum in London, and the T3, T4, and Rover-BRM racing car at the Heritage Motor Centre at Gaydon. The truck survives in private hands, having been restored, and is a regular sight at summer time shows.

As a footnote to the Rover story, in response to the development of JET1 at the start of the 1950s, their rival and later British Leyland stablemate Austin developed their own gas turbine car. If international readers find Jet1’s styling a bit quaint compared to the American jet cars, it is positively space-age when compared to the stately home styling of the Sheerline limousine to which Austin fitted their gas turbine.

Rover T4 gas turbine header image: Matthias v.d. Elbe [CC BY-SA 3.0].

Inductive Loop Vehicle Detector Gets Modernized

Much like George Lucas and the original Star Wars films, many of us may find that our passion projects are never quite finished, especially when new technology comes around or we just want to make some improvements for their own sake. [Muris] was featured a while back for a vehicle detecting circuit, but is back with some important upgrades to his project. (Which, luckily, do not include any horrible CGI aliens.)

For starters, the entire project has been reworked from the ground up. For anyone unfamiliar with the original project, the circuit detected a vehicle via an inductive loop and was able to perform a task like opening a gate. It now has two independent channels which are polled separately, yet has a reduced parts count which should make construction simpler. The firmware has also been reprogrammed, and in addition to sensing a vehicle’s presence can now also measure the speed of any vehicles passing by.

The complete list of improvements can be found on the project page, and an extensive amount of documentation is available on this if you want to try to roll out your own inductive loop vehicle detector. Of course, this isn’t the only way to detect a vehicle’s presence if inductive loops aren’t really your style.

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The Bane of Aftermarket Car Alarms

The humble car alarm has been around almost as long as the car itself, first being developed by an unknown prisoner in Denver, circa 1913. To the security-conscious motorist, they make a lot of sense. The noise of a car alarm draws attention which is the last thing a would-be thief wants, and the in-built immobilizers generally stop the car being moved at all without a time-consuming workaround. Both are a great deterrent to theft.

It may then surprise you to know that I, dear readers, consider the aftermarket car alarm to be one of the most heinous devices ever fitted to the modern automobile. Combining the unholy trifecta of being poorly designed, cheaply made, and fitted by only the most untalented or uncaring people to wield a soldering iron, they are a blight that I myself refuse to accept.

It was my very own Mazda that suffered at the hands of a car alarm system. Two days after purchasing the car, the keyfob died, and thus the car would no longer start. My other car was already out of action due to bent valves, and I needed to get to work, so I figured as a competent hacker, I’d be able to quickly disable it.

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Earth Rovers Explore Our Own Planet

While Mars is currently under close scrutiny by NASA and other space agencies, there is still a lot of exploring to do here on Earth. But if you would like to explore a corner of our own planet in the same way NASA that explores Mars, it’s possible to send your own rover to a place and have it send back pictures and data for you, rather than go there yourself. This is what [Norbert Heinz]’s Earth Explorer robots do, and anyone can drive any of the robots to explore whatever locations they happen to be in.

A major goal of the Earth Explorer robot is to be easy to ship. This is a smaller version of the same problem the Mars rovers have: how to get the most into a robot while having as little mass as possible. The weight is kept to under 500g, and the length, width, and height to no more than 90cm combined. This is easy to do with some toy cars modified to carry a Raspberry Pi, a camera, and some radios and sensors. After that, the robots only need an interesting place to go and an Internet connection to communicate with Mission Control.

[Norbert] is currently looking for volunteers to host some of these robots, so if you’re interested head on over to the project page and get started. If you’d just like to drive the robots, though, you can also get your rover fix there as well. It’s an interesting project that will both get people interested in exploring Earth and in robotics all at the same time. And, if you’d like to take the rover concept beyond simple exploration, there are other machines that can take care of the same planet they explore.

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Make Cars Safer By Making Them Softer

Would making autonomous vehicles softer make them safer?

Alphabet’s self-driving car offshoot, Waymo, feels that may be the case as they were recently granted a patent for vehicles that soften on impact. Sensors would identify an impending collision and adjust ‘tension members’ on the vehicle’s exterior to cushion the blow. These ‘members’ would be corrugated sections or moving panels that absorb the impact alongside the crumpling effect of the vehicle, making adjustments based on the type of obstacle the vehicle is about to strike.

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Spoiler Alert! Repairing A Race Car Can Get Complicated, Fast.

[Big Fish Motorsports] has a vehicle with an adjustable rear spoiler system that broke in the lead up to a big race. The original builder had since gone AWOL so the considerable talents of [Quinn Dunki] were brought to bear in getting it working again.

Cracking open the black control box of mystery revealed an Arduino, a ProtoShield and the first major road block: the Arduino remained stubbornly incommunicado despite several different methods of trying to read the source code. Turns out the Arduino’s ATMega324 was configured to be unreadable or simply fried, but an ATMega128 [Quinn] had proved to be a capable replacement. However, without knowing how the ten relays for this spoiler system were configured — and the race day deadline looming ever larger — [Quinn] opted to scrap the original and hack together something of her own design with what she had on hand.

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Wideband Woes and the Junkbox Miata

As ever, I am fighting a marginally winning battle against my 1991 Mazda MX-5, and this is the story of how I came to install a wideband oxygen sensor in my Japanese thoroughbred. It came about as part of my ongoing project to build myself a viable racecar, and to figure out why my 1990s Japanese economy car engine runs more like a late 1970s Malaise-era boat anchor.

I’ve always considered myself unlucky. My taste for early 90s metal has meant I’ve never known the loving embrace of OBD-2 diagnostics, and I’ve had to make to do with whatever hokey system was implemented by manufacturers who were just starting to produce reliable fuel injection systems.

Narrowband oxygen sensor voltage output. The output is heavily dependent on sensor temperature and highly non-linear, making these sensors unsuitable for delivering a true AFR reading.

This generally involves putting in a wire jumper somewhere, attaching an LED, and watching it flash out the trouble codes. My Mazda was no exception, and after putting up with a car that was running rich enough to leave soot all over the rear bumper, I had to run the diagnostic.

It turned up three codes – one for the cam angle sensor, and two for the oxygen sensor. Now, a cam angle sensor (CAS) fault will normally prevent the car running at all, so it’s safe to assume that was an intermittent fault to keep an eye on.

The oxygen sensor, however, was clearly in need of attention. Its job is to allow the engine control unit (ECU) to monitor the fuel mixture in the exhaust, and make sure it’s not too rich or too lean. As my car was very obviously running too rich, and the diagnostic codes indicated an oxygen sensor failure, a repair was in order.

I priced up replacement sensors, and a new oxygen sensor could be had for under $100. However, it wasn’t exactly what I wanted, as not all oxygen sensors are created equal. Cars in the 80s and 90s typically shipped from the OEM fitted with what’s called a narrowband oxygen sensor. These almost always consist of a zirconia dioxide cell that outputs a voltage depending on the difference in oxygen concentration between the exhaust gas and the free air. These sensors generally sit at 0.45 V when the fuel mixture is stoichiometric, but rapidly change to 0.1 V in a lean condition and 0.9 V in a rich condition. The response is highly non-linear, and changes greatly with respect to temperature, and thus is only good for telling the ECU if it’s rich or lean, but not by how much. ECUs with narrowband sensors tend to hunt a lot when running in closed loop O2 control – you’ll see an engine at idle hunt either side of the magical 14.7 stoichiometric air fuel ratio, never able to quite dial in on the correct number.

As I intend to switch to an aftermarket ECU in the future, I’ll need to tune the car. This involves making sure the air/fuel ratios (AFRs) are correct, and for that I need to be able to properly measure them. Just knowing whether you’re rich or lean isn’t enough, as often it’s desirable to run the engine intentionally rich or lean at certain engine loads. To get a true AFR reading requires fitting a wideband oxygen sensor. These are a little more complicated.

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